Re: [Bug 12832] New: kernel leaks a lot of memory

[Wu Fengguang <fengguang.wu@intel.com>]

On Wed, Mar 11, 2009 at 05:02:23PM +0200, Pierre Ossman wrote:
> On Wed, 11 Mar 2009 21:00:22 +0800
> Wu Fengguang <fengguang.wu@intel.com> wrote:
> 
> > 
> > I worked up a simple debugging patch. Since the missing pages are
> > continuously spanned, several stack dumping shall be enough to catch
> > the page consumer.
> > 
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 27b8681..c0df7fd 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -1087,6 +1087,13 @@ again:
> >  			goto failed;
> >  	}
> >  
> > +	/* wfg - hunting the 40000 missing pages */
> > +	{
> > +		unsigned long pfn = page_to_pfn(page);
> > +		if (pfn > 0x1000 && (pfn & 0xfff) <= 1)
> > +			dump_stack();
> > +	}
> > +
> >  	__count_zone_vm_events(PGALLOC, zone, 1 << order);
> >  	zone_statistics(preferred_zone, zone);
> >  	local_irq_restore(flags);
> 
> This got very noisy, but here's what was in the ring buffer once it had
> booted.

It's about 20 stack dumps, hehe. Could you please paste some of them?
Thank you!

> Note that this is where only the "noflags" pages have been allocated,
> not "lru".

The lru pages have even numbered pfn, the noflags pages have odd
numbered pfn. So if it's 1-page allocations, the ((pfn & 0xfff) <= 1)
will match both lru and noflags pages.

Thanks,
Fengguang

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